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6.12 Asynchronous methods

The Task-based Asynchronous Pattern (TAP) is a pattern for asynchrony in the .NET Framework. It is based on the Task and Task<TResult> types in the System.Threading.Tasks namespace, which are used to represent arbitrary asynchronous operations.

Async-Await are new keywords introduced to work with the TAP. The Async modifier is used to specify that a method, lambda expression, or anonymous method is asynchronous. The Await operator is applied to a task in an asynchronous method to suspend the execution of the method until the awaited task completes.

Requirements

  • Async-Await support requires .NET Framework 4.5 or greater

  • TAP support requires .NET Framework 4.0 or greater

  • Connector/Net 6.9 or greater

Methods

These methods can be used with either TAP or Async-Await.

  • Namespace MySql.Data.Entity

    • Class EFMySqlCommand

      • Task PrepareAsync()

      • Task PrepareAsync(CancellationToken)

  • Namespace MySql.Data

    • Class MySqlBulkLoader

      • Task<int> LoadAsync()

      • Task<int> LoadAsync(CancellationToken)

    • Class MySqlConnection

      • Task<MySqlTransaction> BeginTransactionAsync()

      • Task<MySqlTransaction> BeginTransactionAsync (CancellationToken)

      • Task<MySqlTransaction> BeginTransactionAsync(IsolationLevel)

      • Task<MySqlTransaction> BeginTransactionAsync (IsolationLevel , CancellationToken)

      • Task ChangeDatabaseAsync(string)

      • Task ChangeDatabaseAsync(string, CancellationToken)

      • Task CloseAsync()

      • Task CloseAsync(CancellationToken)

      • Task ClearPoolAsync(MySqlConnection)

      • Task ClearPoolAsync(MySqlConnection, CancellationToken)

      • Task ClearAllPoolsAsync()

      • Task ClearAllPoolsAsync(CancellationToken)

      • Task<MySqlSchemaCollection> GetSchemaCollection(string, string[])

      • Task<MySqlSchemaCollection> GetSchemaCollection(string, string[], CancellationToken)

    • Class MySqlDataAdapter

      • Task<int> FillAsync(DataSet)

      • Task<int> FillAsync(DataSet, CancellationToken)

      • Task<int> FillAsync(DataTable)

      • Task<int> FillAsync(DataTable, CancellationToken)

      • Task<int> FillAsync(DataSet, string)

      • Task<int> FillAsync(DataSet, string, CancellationToken)

      • Task<int> FillAsync(DataTable, IDataReader)

      • Task<int> FillAsync(DataTable, IDataReader, CancellationToken)

      • Task<int> FillAsync(DataTable, IDbCommand, CommandBehavior)

      • Task<int> FillAsync(DataTable, IDbCommand, CommandBehavior, CancellationToken)

      • Task<int> FillAsync(int, int, params DataTable[])

      • Task<int> FillAsync(int, int, params DataTable[], CancellationToken)

      • Task<int> FillAsync(DataSet, int, int, string)

      • Task<int> FillAsync(DataSet, int, int, string, CancellationToken)

      • Task<int> FillAsync(DataSet, string, IDataReader, int, int)

      • Task<int> FillAsync(DataSet, string, IDataReader, int, int, CancellationToken)

      • Task<int> FillAsync(DataTable[], int, int, IDbCommand, CommandBehavior)

      • Task<int> FillAsync(DataTable[], int, int, IDbCommand, CommandBehavior, CancellationToken)

      • Task<int> FillAsync(DataSet, int, int, string, IDbCommand, CommandBehavior)

      • Task<int> FillAsync(DataSet, int, int, string, IDbCommand, CommandBehavior, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string, IDataReader)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, string, IDataReader, CancellationToken)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, IDbCommand, string, CommandBehavior)

      • Task<DataTable[]> FillSchemaAsync(DataSet, SchemaType, IDbCommand, string, CommandBehavior, CancellationToken)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, CancellationToken)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDataReader)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDataReader, CancellationToken)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDbCommand, CommandBehavior)

      • Task<DataTable> FillSchemaAsync(DataTable, SchemaType, IDbCommand, CommandBehavior, CancellationToken)

      • Task<int> UpdateAsync(DataRow[])

      • Task<int> UpdateAsync(DataRow[], CancellationToken)

      • Task<int> UpdateAsync(DataSet)

      • Task<int> UpdateAsync(DataSet, CancellationToken)

      • Task<int> UpdateAsync(DataTable)

      • Task<int> UpdateAsync(DataTable, CancellationToken)

      • Task<int> UpdateAsync(DataRow[], DataTableMapping, CancellationToken)

      • Task<int> UpdateAsync(DataSet, string)

      • Task<int> UpdateAsync(DataSet, string, CancellationToken)

    • Class MySqlHelper

      • Task<DataRow> ExecuteDataRowAsync(string, string, params MySqlParameter[])

      • Task<DataRow> ExecuteDataRowAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(string, string, params MySqlParameter[])

      • Task<int> ExecuteNonQueryAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<DataSet> ExecuteDatasetAsync(string, string)

      • Task<DataSet> ExecuteDatasetAsync(string, string, CancellationToken)

      • Task<DataSet> ExecuteDatasetAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string)

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string, CancellationToken)

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<DataSet> ExecuteDatasetAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

      • Task UpdateDataSetAsync(string, string, DataSet, string)

      • Task UpdateDataSetAsync(string, string, DataSet, string, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, MySqlTransaction, string, MySqlParameter[], bool)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, MySqlTransaction, string, MySqlParameter[], bool, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string)

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string)

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string, CancellationToken)

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string, params MySqlParameter[])

      • Task<MySqlDataReader> ExecuteReaderAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<MySqlDataReader> ExecuteReaderAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(string, string)

      • Task<object> ExecuteScalarAsync(string, string, CancellationToken)

      • Task<object> ExecuteScalarAsync(string, string, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(string, string, CancellationToken, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(MySqlConnection, string)

      • Task<object> ExecuteScalarAsync(MySqlConnection, string, CancellationToken)

      • Task<object> ExecuteScalarAsync(MySqlConnection, string, params MySqlParameter[])

      • Task<object> ExecuteScalarAsync(MySqlConnection, string, CancellationToken, params MySqlParameter[])

    • Class MySqlScript

      • Task<int> ExecuteAsync()

      • Task<int> ExecuteAsync(CancellationToken)

In addition to the methods listed above, the following are methods inherited from the .NET Framework:

  • Namespace MySql.Data.Entity

    • Class EFMySqlCommand

      • Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehaviour, CancellationToken)

      • Task<int> ExecuteNonQueryAsync()

      • Task<int> ExecuteNonQueryAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync()

      • Task<DbDataReader> ExecuteReaderAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour, CancellationToken)

      • Task<object> ExecuteScalarAsync()

      • Task<object> ExecuteScalarAsync(CancellationToken)

  • Namespace MySql.Data

    • Class MySqlCommand

      • Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehaviour, CancellationToken)

      • Task<int> ExecuteNonQueryAsync()

      • Task<int> ExecuteNonQueryAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync()

      • Task<DbDataReader> ExecuteReaderAsync(CancellationToken)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour)

      • Task<DbDataReader> ExecuteReaderAsync(CommandBehaviour, CancellationToken)

      • Task<object> ExecuteScalarAsync()

      • Task<object> ExecuteScalarAsync(CancellationToken)

    • Class MySqlConnection

      • Task OpenAsync()

      • Task OpenAsync(CancellationToken)

    • Class MySqlDataReader

      • Task<T> GetFieldValueAsync<T>(int)

      • Task<T> GetFieldValueAsync<T>(int, CancellationToken)

      • Task<bool> IsDBNullAsync(int)

      • Task<bool> IsDBNullAsync(int, CancellationToken)

      • Task<bool> NextResultAsync()

      • Task<bool> NextResultAsync(CancellationToken)

      • Task<bool> ReadAsync()

      • Task<bool> ReadAsync(CancellationToken)

Examples

The following examples demonstrate how to use the Asynchronous methods:

In this example, a method has the "async" modifier because the method "await" call made applies to the method LoadAsync. The method returns a Task which contains information about the result of the awaited method. Returning Task is like having a void method, but you should not use "async void" if your method is not a top level access method, like an event.


public async Task BulkLoadAsync()
{
  MySqlConnection myConn = new MySqlConnection("MyConnectionString");
  MySqlBulkLoader loader = new MySqlBulkLoader(myConn);

  loader.TableName       = "BulkLoadTest";
  loader.FileName        = @"c:\MyPath\MyFile.txt";
  loader.Timeout         = 0;

  var result             = await loader.LoadAsync();

}

        

In this example, an "async void" method is used with "await" for the ExecuteNonQueryAsync method, to correspond to the onclick event of a button. This is why the method does not return a Task.


private async void myButton_Click()
{
  MySqlConnection myConn = new MySqlConnection("MyConnectionString");
  MySqlCommand proc      = new MySqlCommand("MyAsyncSpTest", myConn);

  proc.CommandType       = CommandType.StoredProcedure;

  int result             = await proc.ExecuteNonQueryAsync();
}


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